Fig. 1.

The effects of l-dopa on pancreatic islet dopamine content in vitro and in vivo. A and B, The dopamine content of pancreatic islets was measured immediately after isolation and after incubation in presence (■) (A) (n = 4–7) or absence (□) (B) (n = 3–4) of 10 μm l-dopa for different time intervals. *, P < 0.05; **, P < 0.01; ***, P < 0.001 vs. incubation time = 0 h. C, The dopamine content of pancreatic islets was measured after a 30-min incubation in presence of 50 μm benserazide, 10 μm l-dopa, and a combination of 50 μm benserazide + 10 μm l-dopa (n = 2–3). **, P < 0.01 vs. 50 μm benserazide; ^#, P < 0.05 vs. 10 μm l-dopa. D, The dopamine content of pancreatic islets was measured immediately after isolation from mice that have received an ip injection of saline solution or 50 mg/kg of l-dopa 30 min before surgery (n = 2). ***, P < 0.001 vs. saline.